"Traditionally, a pilgrimage has been understood as a journey that takes one progressively away from “the world,” towards a famed spiritual center – Lourdes, for example, or the Holy Land, or, as in Chaucer's case, Canterbury. That’s the sense in which people today still refer to a pilgrimage to Medjugorje, or to San Giovanni Rotondo, the principal shrine of Padre Pio in southern Italy.

In the beginning, World Youth Days were conceived as pilgrimages in this classic sense. The 1989 edition, for example, was held in Santiago de Compostela in Spain, and in 1991 Catholic youth converged upon the famed Polish shrine of the Black Madonna in Cz?stochowa. Both have been traditional pilgrimage destinations for centuries.

Along the way, however, something unexpected happened. Turnout exceeded even high-end estimates, and the youthful passion of the pilgrims elicited strong media interest. As a result, World Youth Day went from being largely an inner-Catholic affair to a "happening" that captured the imagination of the broader culture.

In the wake of those experiences, church officials began to grasp that the value of World Youth Day lies not only in the spiritual formation it offers to young people, but also the evangelical witness those young people offer to the world.

One could date the emergence of World Youth Day as a model of "Evangelical Pilgrimage" to 1993. In that year, the event was held in Denver, Colorado, hardly anyone’s idea of a traditional pilgrimage center. In the years since, World Youth Days have been held in such disparate locales as Paris, Toronto, Cologne, and now Sydney. Some might be considered traditional pilgrimage destinations and some not, but that’s no longer the common term.

Rather, sites now seem to be chosen for World Youth Days not because they’re seen as reservoirs of spiritual energy, but rather because they’re suffering from spiritual drought. In other words, the aim is not to escape secularism, but rather to challenge it on its home turf.

By all accounts, Denver was the key to this paradigm shift. Prior to the event, staging World Youth Day in a city without a strong Catholic culture, and with a strongly secular ethos, was considered an enormous gamble. Behind the scenes, organizers and Vatican officials worried about low turnout and public indifference.

In the end, the event was perceived as a huge success that energized the local church.

“Looking back, the church in northern Colorado is dramatically different” because of what happened at World Youth Day, Archbishop Charles Chaput of Denver said in 2002. Among other things, Chaput said that Denver’s two seminaries were “literally running out of room for candidates,” one expression of a renewal that he traced to 1993."

It is hard to imagine a more powerful evangelical tool than WYD in the day of the internet and 24/7 streaming video.

It is interesting that Allen has just moved his family to Denver this summer, to escape the impossible cost of housing in New York. One of the most vibrant centers of "new Catholicism" in the country.